Method for gasifying and gasifying unit

ABSTRACT

A method for gasifying, whereby a gasifying unit is being exploited, wherein solid fuel, being fed thereto, is being gasified in a fire-box lined, throttled gasifying space, in which gasifying air is being brought by a primary air distribution assembly that exists at least partly on its lined wall section. The gasifying air is led into a primary space that surrounds the gasifying space, when viewed in a cross section, essentially from all over and that brings about cooling of the gasifying unit&#39;s casing and the gasifying air to get steady before it is led into the gasifying space through the primary air distribution assembly. Also a gasifying unit operating according to the method.

The invention relates to a method for gasifying, whereby a gasifying unit is being exploited, wherein solid fuel, being fed thereto, is being gasified in a fire-box lined, throttled gasifying space, in which gasifying air is being brought by means of a primary air distribution assembly that exists at least partly on its lined wall section.

In Finnish patent number 20019 there has been presented a type of gasifying apparatus as described above, which has rings made of fireproof structures, between which an air distribution ring made of metal is placed in order to feed primary air into the gasifying space.

In a gasifying process, feeding of air into the gasifying space must be carried in a way that the air, being led to the bed to be gasified, is distributed as evenly as possible. This is why, the air distribution ring, being exploited in the patent mentioned above, has been carried out by a rather complicated structure, which has several parallel distribution pipes in order to achieve an air flow in the air distribution ring as even as possible. A further problem related to this type of solution in addition to its complexity, is due to the fact that this type of an air distribution ring is not very long lasting, which is why in the patent in question there has been suggested to carry out the same by a structure that is assembled in its place removeably, so that it can be replaced easily. On the other hand, a matter of fact in practice is that the nozzles are the most vulnerable components in traditional gasifiers. This is due to the fact that by the nozzles first of all hot points get generated, in which the fuel gets melted and crushed. On the other hand, cool zones will be left between the nozzles, from which the fuel may enter into the reduction zone without pyrolysis.

It is an aim of the present method to achieve a decisive improvement in the problems described above and thus to raise essentially the level of prior art. In order to achieve this aim, the method according to the invention is mainly characterized by that gasifying air is being led into a primary space that surrounds the gasifying space, when viewed in a cross section, essentially from all over and that brings about cooling of the gasifying unit's casing and the gasifying air to get steady before it is led into the gasifying space through the primary air distribution assembly.

As the most important advantages of the method according to the invention may be mentioned simplicity and efficiency of its operation as well as of the structure enabled by the same, wherein by means of very simple solutions, that is by a primary space, surrounding the gasifying space, it is possible to make sure first of all efficient cooling of the casing of the gasifying unit by bringing about simultaneously an optimum even feeding of the gasifying air into the gasifying space. Thanks to the method according to the invention, it is thus possible to carry out first of all the primary air distribution assembly in an extremely simple way by means of an air distribution opening, existing on the walls of the gasifying space and that is essentially open from all over and being placed between the gasifying space and a fireproof junction part, existing in connection with a lower part of a reception space. A “nozzleless” feeding of air, being carried out according to the method of the invention, makes possible an even air distribution over the whole area of the reactor, thanks to which those nozzle problems related to traditional gasifiers may be avoided. In this connection, a large air distribution area makes possible among other things use of peat and of other fuels as well, containing ash that gets easily melted. As an advantageous embodiment of the method, it is furthermore possible to exploit a secondary air distribution assembly that is placed internally with respect to the solid fuel that is to be fed into the gasifying space, which for its part also furthers distribution of air evenly into the fuel bed to be gasified.

Advantageous embodiments of the method according to the invention have been presented in the dependent claims related to the same.

The invention relates also to a gasifying unit operating according to the method and being described in a greater detail in the preamble of the independent claim related to the same. Those characteristic features of the gasifying unit according to the invention have been presented in the characterizing part of the corresponding independent claim.

As the most important advantages of the gasifying unit according to the invention may be mentioned the simplicity and reliability of its structure and use. A primary space, surrounding the gasifying space, when viewed in a cross section, essentially from all over, makes possible a very efficient cooling of the gasifying unit's casing and on the other hand also an optimum feeding of the gasifying air into the gasifying space in a way, that the primary air can be fed into the fuel, existing in the gasifying space, from all over as evenly as possible. As an advantageous embodiment of the gasifying unit according to the invention, there has been exploited a secondary air distribution channel, operating from above and being placed centrically, which for its part balances further the distribution of air by feeding the same in an opposite direction with respect to the primary air that is outwards from the center of the fuel bed. Also the primary air distribution assembly of a gasifying unit according to the invention may be carried out for its part structurally in an extremely advantageous way without extra nozzle structures e.g. made of metal, thanks to which, it does not require extra maintenance, either. One crucial advantage of the gasifying unit according to the invention is also the fact that those hot and cool zones, existing between the nozzles, that are typical for traditional solutions, can be avoided thanks to a “nozzleless” distribution of air according to the invention, which makes possible an even heat distribution and an optimum gasifying process in terms of homogeneity over the whole area of the reactor.

Advantageous embodiments of the gasifying unit according to the invention have been presented in the dependent claims related to the same.

In the following description, the invention is being illustrated with reference to the appended drawing, which shows on a principle level an advantageous cross section of a gasifying unit operating according to the method of the invention.

The invention relates to a method for gasifying, whereby a gasifying unit is being exploited, wherein solid fuel, being fed thereto, is being gasified in a fire-box lined, throttled gasifying space K, in which gasifying air is being brought by means of a primary air distribution assembly that exists at least partly on its lined wall section. According to appended drawing, the gasifying air is being led into a primary space P that surrounds the gasifying space K, when viewed in a cross section, essentially from all over and that brings about cooling of the gasifying unit's casing and the gasifying air to get steady before it is led into the gasifying space through the primary air distribution assembly.

As an advantageous embodiment, secondary air is being led into the gasifying space K internally with respect to the solid fuel to be fed into the gasifying space K through a secondary air distribution assembly II, being placed advantageously centrically.

The method according to claim 1 is being applied advantageously in connection with a gasifying unit, which comprises a built-in reception space T for the solid fue to be gasified, in which context as a further advantageous embodiment of the invention, the primary air distribution assembly is being formed of an air distribution opening I, existing on the wall of the gasifying space K essentially open from all over and being placed between the gasifying space K and a fireproof junction part O, existing in connection with a lower part of the reception space T.

Furthermore as an advantageous embodiment, the lining of the gasifying space K and the junction part O is being produced from ceramic material as a single piece structure or made of several parts.

The invention relates to gasifying unit, too, which has a fire-box lined, throttled gasifying space K for gasifying of sold fuel, being fed thereto. Gasifying air is brought into the gasifying space K by means of a primary air distribution assembly that exists at least partly on its lined wall section. With reference to the appended drawing, the gasifying space is provided with a primary space P that surrounds the gasifying space K, when viewed in a cross section essentially from all over and that brings about cooling of the gasifying unit's casing and the gasifying air to get steady before it is led into the gasifying space through the primary air distribution assembly. As an advantageous embodiment of the invention, the gasifying unit comprises a secondary air distribution assembly II, being placed internally with respect to the solid fuel to be fed into the gasifying space K, for leading of secondary air into the gasifying space K. The secondary air distribution assembly II is carried out in the advantageous embodiment, shown in the drawing, by an upper air channel, being placed centrically.

As an advantageous embodiment of the gasifying unit according to the invention, the same comprises a built-in reception space T for the solid fuel to be gasified, in which case the primary air distribution assembly is formed advantageously of an air distribution opening I, existing on the wall of the gasifying space K essentially open from all over and being placed between the gasifying space K and a fire proof junction part O, existing in connection with a lower part of the reception space T.

The lining of the gasifying space K and the junction part O is produced as an advantageous embodiment from ceramic material as a single piece structure or made of several parts.

It is clear that the invention is not limited to the embodiments presented or described above, but it can be modified within the basic idea of the invention according to the purposes and embodiments at any given time and depending on the solid fuel to be used respectively. It is thus clear first of all that the lower grating A of the gasifying unit, such as the base grating or like, may be carried out both with solid structures and moveable mechanisms. The cross section of the structure shown in the appended drawing is for its part meant to depict the present invention mainly on principle level, so that the structural solutions and dimensions therewith are mostly of guide-like character. In the appended drawing there has not been shown in greater detail the lower structures of the gasifying unit, either, because they are not that essential as such from the point of view of the present invention. 

1. A method for gasifying, whereby a gasifying unit is being exploited, wherein solid fuel, being fed thereto, is being gasified in a fire-box lined, throttled gasifying space, in which gasifying air is being brought by means of a primary air distribution assembly that exists at least partly on its lined wall section, and whereby the gasifying air is being led into a primary space that surrounds the gasifying space, when viewed in a cross section, essentially from all over and that brings about cooling of the gasifying unit's casing and the gasifying air to get steady before it is led into the gasifying space through the primary air distribution assembly, wherein secondary air is being led into the gasifying space internally with respect to the solid fuel to be fed into the gasifying space through a secondary air distribution assembly, being placed preferably centrically.
 2. The method according to claim 1 in connection with a gasifying unit, which comprises a built-in reception space for the solid fuel to be gasified, wherein the primary air distribution assembly is being formed of an air distribution opening, existing on the wall of the gasifying space essentially open from all over and being placed between the gasifying space and a fireproof junction part, existing in connection with a lower part of the reception space.
 3. The method according to claim 2, wherein the lining of the gasifying space and the junction part is being produced from ceramic material as a single piece structure or made of several parts.
 4. A gasifying unit, comprising: a fire-box lined, throttled gasifying space for gasifying of sold fuel, being fed thereto and, into which gasifying air is brought by means of a primary air distribution assembly that exists at least partly on its lined wall section, a primary space that surrounds the gasifying space, when viewed in a cross section essentially, from all over and that brings about cooling of the gasifying unit's casing and the gasifying air to get steady before the gasifying air is led into the gasifying space through the primary air distribution assembly, and a secondary air distribution assembly arranged internally with respect to the solid fuel to be fed into the gasifying space for leading of secondary air into the gasifying space.
 5. A gasifying gasifying unit according to claim 4, wherein the secondary air distribution assembly comprises an upper air channel, being placed centrically.
 6. A gasifying unit according to claim 4, further comprising: a built-in reception space for the solid fuel to be gasified, wherein the primary air distribution assembly comprises an air distribution opening, existing on the wall of the gasifying space essentially open from all over and being placed between the gasifying space and a fire proof junction part, existing in connection with a lower part of the reception space.
 7. A gasifying unit according to claim 6, wherein the lining of the gasifying space and the junction part comprises ceramic material as a single piece structure or made of several parts. 